40 ZOOPHYTES. 
openings scattered over it, each of which is the centre of a slightly- 
raised prominence. On expanding, these openings enlarge, the mar- 
gin of each rolls back, and finally the whole mass, before seeming 
lifeless, is covered with radiated disks, half an inch broad, having a 
lilac centre, and bordered with a fringe of short tentacles. ‘These are 
the flower-animals—the polyps—of the Palythoa. ‘They are repre- 
sented of the natural size in figure 3. Some of the polyps on the 
right are yet closed, while others are partly, and others wholly, ex- 
panded. An enlarged view of the expanded polyp is shown in figure 
3a, exhibiting the circular disk—the fringe of short tumid tentacles, 
in two series, one directed more upward than the other—and, upon 
the disk, elevated greenish lines, extending, like radi, from each ten- 
tacle to the convex centre in which the mouth is situated. The tex- 
ture of the general mass of the zoophyte is peculiar, in consisting of 
coral sand agglutinated by animal matter; particles of various colours 
are here mingled,—white, red, and black. The sand, as it falls upon 
the growing zoophyte, is enclosed by the slimy secretions of the sur- 
face, and is finally introduced into its texture; and thus firmness is 
secured by calcareous granules from a foreign source. This is im- 
perfectly represented in the figures 3 6 and 3 c. 
31. The tentacles are naked—that is, without papille—as in the 
Actiniw, and each has a minute puncture at apex. ‘These organs are 
tubular, and they communicate internally with the visceral cavity 
through a duct concealed under the radiated lines of the disk. ‘The 
mode of expansion by injection with water is the same as in the 
animals above described.. The mouth is without appendages of any 
kind—a simple opening through the fleshy disk. 
32. The visceral cavity is cylindrical, and extends down below the 
disk, into the polyp-mass, to its base. Its form and size, as com- 
pared with the expanded animal, is shown in figure 3@. The mouth 
opens into this cavity, through an oblong stomach, which is about 
one-fifth the length of the cavity, and is connected with its walls by a 
series of radiating fleshy lamelle, as in the Actinia. ‘There is also 
another series of smaller lamellw intermediate between these. ‘The 
stomach has a vertically striated or plaited structure within, and 
closes at bottom at the will of the animal. Figure 34 is a vertical 
section of the unexpanded polyp, through the mouth (opposite 0’) 
and stomach (0’ to c’), and the general visceral cavity ; and figure 
3d is a transverse section, cutting across the esophagus a little 
